Don't clear btpo_cycleid during _bt_vacuum_one_page.
When "vacuuming" a single btree page by removing LP_DEAD tuples, we are not
actually within a vacuum operation, but rather in an ordinary insertion
process that could well be running concurrently with a vacuum. So clearing
the cycleid is incorrect, and could cause the concurrent vacuum to miss
removing tuples that it needs to remove. This is a longstanding bug
introduced by commit e6284649b9e30372b3990107a082bc7520325676 of
2006-07-25. I believe it explains Maxim Boguk's recent report of index
corruption, and probably some other previously unexplained reports.
In 9.0 and up this is a one-line fix; before that we need to introduce a
flag to tell _bt_delitems what to do.
Branch
------
REL8_4_STABLE
Details
-------
http://git.postgresql.org/pg/commitdiff/7b6a37f5ec2e99e70715a34916eac78bad928def
Modified Files
--------------
src/backend/access/nbtree/nbtinsert.c | 2 +-
src/backend/access/nbtree/nbtpage.c | 10 ++++++----
src/backend/access/nbtree/nbtree.c | 2 +-
src/include/access/nbtree.h | 2 +-
4 files changed, 9 insertions(+), 7 deletions(-)